The objectives of this research program are to: 1) experimentally determine the structural characteristics of he human knee; and 2) to use this data to develop a computer model of the knee for injury investigations and possible reconstructive surgeries. The experimental approach has been developed to be consistent with a 12 by 12 stiffness model of the knee. Loading fixtures interface with an MTS electro-hydraulic load frame to apply fixed displacements while all twelve forces and moments are measured by dynamometers. The loading fixtures allow for many initial joint orientations before the primary displacement is applied. The considerable volume of data is digitized and reduced by an in-lab mini computer. Four section, least squared cubic splines with a specially developed smoothing technique have been developed to model the load displacement curves. The first derivative of these curves provides stiffness vs. displacement curves. The experiments will be conducted with intact and sectioned knees and with instrumented ligaments to determine the contribution of specific elements to joint stiffness. Thus, joint load-displacement and ligament loading due to external loads can be determined. Storage effects on structural characteristics will also be studied.